Pavers OVER Asphalt?

My dad was in Baltimore on Thursday and at one of the Medical centers he noticed an asphalt crew working with a paver crew. He said it appeared that the asphalt was the base for the pavers. The asphalt was being tamped and he said no sand was on the job and the crew was laying pavers. Why would pavers be over asphalt?

This is a coommon practice for streets and parking lots. Asphalt is a suitable setting bed for pavers and can be very cost effective on larger jobs. A paving machine screeds the path and the ICP follows behind them.

Hanover Arch. Products makes both concrete and asphalt pavers. One of there specs allows for the pavers to be set on a asphalt setting bed. This is also called sheet asphalt. It is concrete sand and asphalt tar mixed in a hot mixing plant. As a setting bed it is expensive. Not all asphalt plants offer this mix. After this setting is screeded it has to be rolled. You must use a small roller or it will push out the setting bed. Then a neoprene glue is spread very thin on top of setting bed. The pavers are then laid and sand swept into the joints.